Thrust-reversing apparatus for turbofan jet engine

ABSTRACT

Turbofan jet engine fan air is discharged through passage between engine housing and cowling spaced therearound. Doors are pivoted to inner and outer sides of cowling adjacent aft edges of openings spaced circumferentially thereof and move between a retracted position closing the openings and a deployed position extending laterally therefrom, the inner doors blocking the fan air passage and deflecting fan air through the openings in the deployed position and the outer doors deflecting the fan air forwardly to reverse thrust. During deployment the inner doors completely block fan air passage only after outer doors are fully deployed, and when doors are retracted the inner doors open the fan air passage slightly before outer doors begin to close.

United States Patent Peter H. Ellis;

[72] Inventors Samuel 1. Persky, both of Chula Vista,

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through passage between engine housing and cowling spaced therearound.Doors are pivoted to inner and outer sides of Cowling adjacent aft edgesof openings spaced circum- 139/26539, ferentially thereof and movebetween a retracted position 60/229 closing the openings and a deployedposition extending [51] hit. B64C15/04 [Me -an th f m the inner doorsbldcking the fan air Fleld of passage and deflecting fan air through theOpenings in the 2651916531, deployed position and the outer doorsdeflecting the fan air 229,230139-23 forwardly to reverse thrust. Duringdeployment the inner doors completely block fan air passage only afterouter doors [56] References Cited UNITED STATES PATENTS 11/1969 Mortlocket al.

are fully deployed, and when doors are retracted the inner PATENTED um 1219m SHEET 1 0F a INVENTOR.

w E .LP E I H L RE EU TM A 5 ATTORNEY PATENTEUUEHQIH'I: 3,612,401

' SHEET 2 BF 4 INVENTOR, PETER H. IELLIS SAMUEL I. PERSKY ATTORNEYPATENTEDUCH2ISY 5 2 SHEET 3 0F 4 PEG. 3

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PETER H. ELLIS SAMUEL 1. PERSKY 58 u u M E D, :1

AT TORNEY PATENTEUUCTIZIQYI 3,612,401 SHEET w HF a INVENTOR. ETER H,ELLIS BY SAMUEL I. PERSKY ATTORNEY TI-IRUST-REVERSING APPARATUS FORTURBOFAN .llET ENGINE SUMMARY OF THE INVENTION This invention relates tothrust reversing apparatus for an aircraft turbofan jet engine, and moreparticularly to such apparatus which changes the direction of flow ofengine fan air to effect thrust reversal.

Apparatus which reverses the flow of fan air of a turbofan jet engine toobtain thrust reversal has been used heretofore. However, knownarrangements for this purpose have not been entirely satisfactory due tovarious reasons, including their inability in certain cases to deflectthe fan air forwardly at an angle which will provide effective thrustreversal. Some of the previously proposed fan air thrust reversers alsocomprise excessively complicated and heavy components, as well asactuating mechanisms which interfere with the normal flow of fan airwhen in the retracted position.

In accordance with the invention disclosed herein, thrustreversing doorsare pivoted to the inner and outer sides of a tubular cowling that isconcentrically spaced around a turbofan jet engine housing, pairs ofsaid doors being respectively located adjacent openingscircumferentially spaced about the cowling. When the doors are in aretracted position they close the openings in the cowling and fan air ofthe jet engine is discharged to the atmosphere through the passagebetween the cowling and the engine housing. When the doors are deployedto their thrust-reversing position they swing away from the wall of thecowling and uncover the openings therein, the inner doors deflecting fanair through the latter and the outer doors turning the flow of fan airforwardly relative to the cowling at an angle which provides effectivethrust reversal. The actuating mechanism which develops the doorsrotates the outer doors to their deployed position before the innerdoors completely block the fan air passage, and when the doors areretracted the same mechanism rotates the inner doors away from theirdeployed position before the outer doors begin to close. The outer doorsare provided with sideplates which tend to keep the fan air flowingalong said doors when they are deployed. The described apparatus islight in weight, uncomplicated in construction, and does not interferewith fan airflow when in the inoperative configuration. Thus theinvention provides an improved means for reversing the thrust of aturbofan jet engine by reversing the direction of flow of its fan air.DESCRIPTION OF THE DRAWINGS FIG. ii is a side elevation of the preferredembodiment of the present invention, some of the thrust-reversing doorswhich are incorporated in said embodiment being illustrated in theretracted position thereof and others of said doors being illustrated inthe deployed position thereof, all of the doors being simultaneouslymoved between the two positions in the actual operation of theapparatus;

FIG. 2 is a fragmentary sectional view of two of the thrustreversingdoors in their retracted position;

FIG. 3 is a second view taken at the same plane as that of FIG. 2,illustrating the position assumed by the doors just before they reachtheir deployed position;

FIG. 4 is a third view taken at the same plane as that of FIG. 2,illustrating the deployed position of the doors;

FIG. 5 is a fragmentary sectional view of two of said doors,illustrating the hinges therefor;

FIG. 6 is a cross-sectional of a typical pair of the doors, taken alongthe plane represented by line 6-6 in FIG. 2 and showing sidewallsthereof which are not seen in FIGS. 2-5 wherein components not on thesection planes are omitted in order to simplify the drawings; and

FIG. 7 is a combined rear elevation and sectional view taken along theplane represented by line 7-7 in FIG. 1 and in the direction indicatedby arrows connected thereto.

DETAILED DESCRIPTION In the drawings reference number 10 designatesgenerally a tubular housing which encloses a turbofan jet engine 12 andthe aft end of which defines a thrust nomle 14 for discharge of theexhaust gas of said engine. In the illustrated embodiment of theinvention housing 10 is mounted on a pylon l6 depending from a wing (notshown) of an aircraft. Also mounted on pylon 16 and concentricallyspaced around housing 10 is a tubular cowling, designated generally byreference number 18. More particularly, cowling 18 is formed of twosubstantially hemicylindrical sections 20 (only one shown) which arerespectively pivoted at their upper longitudinal edges 22 to oppositesides of the pylon and the lower longitudinal edges of which are inabutment when the cowling is secured by locking members 24 in itsillustrated operational configuration. The forward end of the cowlingprojects forwardly from the fan section 26 of engine 112, and its aftend terminates at a plane located upstream from the aft end of housing10 and disposed perpendicular to the common longitudinal axis of saidhousing and said cowling. Thus there is a passage 28 between the housingand the cowling through which fan air of the engine is discharged to theatmosphere.

Circumferentially spaced around cowling 18 adjacent its aft end are aplurality of openings 30. These openings are separated from one anotherby narrow, longitudinally extending wall members 32, and their forwardand aft edges are substantially disposed in planes perpendicular to thelongitudinal axis of the cowling. A pair of thrust-reversing doors 34,36 are respectively located on the inner and outer sides of the cowlingadjacent each opening therein. More specifically, as illustrated in FIG.5 a pair of mounting lugs 38 (only one shown) project from the aft edgeof each door 34 at opposite sides thereof, and a pivot pin 40 extendsthrough a hole in each of these lugs and into a hole formed in a bracket42 mounted on the aft edge 44 of the opening 30 with which said door isaligned, the two pivot pins of each door 34 being coaxial. Likewise, apair of mounting lugs 46 (only one shown) project from the aft edge ofeach door 36 at opposite sides thereof, and a pivot pin 48 extendsthrough a hole in each of these lugs and into a hole formed in bracket42, the two pins of each door 36 being coaxial. Thus, both the innerdoors 34 and the outer doors 36 are arranged to pivot about axes lyingin planes perpendicular to the longitudinal axis of the cowling andlocated adjacent the aft edges of openings 30, which permits movement ofthe doors between a retracted position (the upper doors beingillustrated in this position in FIG. I) an a deployed position (thelower doors being illustrated in this position in FIG. I). It will beseen that each door is shaped to conform with the curvature of thecowling when in the retracted position, with the free end of each door34 then abutting a recessed portion 54 of the inner surface of thecowling at the forward edge of the associated opening 30, the free endof each door 36 abutting a recessed portion 56 of the outer surface ofthe cowling at said forward edge, and the side edges of the doorsrespectively lying over the recessed longitudinally extending edges ofwall members 32. Hence doors 34, 36 close the openings in the cowlingwhen in the retracted position. It will also be seen that the innerdoors are shaped so that in the deployed position their free ends lieadjacent the curved surface of housing It] and their side edges arerespectively disposed adjacent one another, said inner doors beinginclined forwardly from the aft edges of the openings in the cowling.When deployed the outer doors 36 are swung outwardly from openings 30and are also inclined forwardly from the aft edges thereof, and thereare narrow gaps between their side edges as can be seen in FIG. I.Deflector plates 58 are respectively fixedly mounted on, and extendacross, the inner side of the outer doors at the free ends thereof, eachplate being perpendicular to the door on which it is mounted. In addition, a sideplate 60 (see FIG. 6) extends along each side edge of eachouter door and is fixedly attached thereto in perpendicular relationwith the adjacent portion of the inner surface of the door.

FIGS. 2-4 show the cross-sectional'shape of a fairing 62 which projectsrearwardly from the inner and outer portions of the forward edge of eachopening 30 in cowling 18. A radially extending slot 64 (see FIG. 1) isformed in the wall of each fairing at the middle thereof, and first andsecond links 66, 68 pass through this slot and are pivoted by means, ofpivot pins 70, 72 to first and second lever arms 74, 76 fixedlyconnected at one end to a drive shaft 78 mounted within the fairing forrotation about its longitudinal axis. The ends of each drive shaft 78are journaled in bearings 80, 82 fixed to support members 84, withinfairing 62, with lever arms 74, 76 being situated between said bearingsand the ends of the drive shaft projecting from the other side thereof.The other ends of each pair of first and second links 66, 68 arerespectively pivoted to the adjacent pair of inner and outer doors 34,36 by means of pivot pins 88, 90 which pass through holes in said linksand holes in lugs 100, 102 respectively fixedly attached to the innersides of said doors at the middle portion thereof. The longitudinal axesof drive shaft 78 and pivot pins 70, 72, 88 and 90 are parallel with thelongitudinal axes of pivot pins 40 and 48, in the mounting and actuatingassembly for each pair of inner and outer doors.

A drive motor 104 is mounted within each section of cowling 18, and rods106 are respectively connected to opposite ends of the drive shafts ofsaid motors. The other ends of rods 106 are connected to universaljoints 108 mounted on the adjacent ends of the drive shafts 78 which arenearest the motors. Rods 110 and universal joints 112 are also employedto interconnect the other drive shafts 78 in the two sections of thecowling with those next to the motors, opening of course being providedin wall members 32 for the rods 106, 110. Power for the motors issupplied through suitable conduits which extend through the cowlingsections to pylon 16.

OPERATION During all periods of operation of the illustrated anddescribed jet propulsion assembly except when reversal of its thrust isrequired; first and second lever arms 74, 76 are positioned asillustrated in FIG. 2 and the first and second links 66, 68 respectivelyconnected to said lever arms hold the inner and outer doors 34, 36 inthe retracted position illustrated in he same drawing. It will be notedthat the arrangement of the disclosed actuation mechanism is such thatwhen the doors are retracted there is nothing within passage 28 tointerfere with the flow of fan air, an advantage not provided withcertain fan air thrust reversers of the prior art.

When reversal of thrust of the described propulsion assembly isrequired, motors 104 are operated to swing the lever arms 74, 76 ondrive shafts 78 rearwardly from the position illustrated in FIG. 2. Whenthe lever arms have rotated to the links illustrated in FIG. 3, eachsecond link 68 is centered, or in line with. the second'lever arm 76 towhich it is connected (i.e., the longitudinal axes of said second linkand said second lever arm, lie in the same plane), and therefore at thisposition each outer door 36 is rotated a maximum distance from cowling18. However, at the same point in the rotation of the lever arms thefirst links are not yet in line with first lever arms 74 and the innerdoors 34 are not fully deployed. As the lever arms continue to rotatetoward the position illustrated in FIG. 4, the outer doors move slightlycloser to the cowling while the inner doors continue to swing inwardlytoward housing 10. When the lever arms reach the FIG. 4 position a limitswitch (not shown) is actuated to stop motors 104. When the inner doorsare fully deployed first links 66 are in line with lever arms 74 and thefree ends of said doors are very close to the surface of housing 10.Thus fan air is then deflected from the inner doors through openings 30and against the outer doors, the latter turning the fan air streamsforwardly to thereby reverse the thrust thereof. A portion of the fanair flowing along each outer door impinges upon the deflector plate 58thereon and is deflected laterally into the remainder of the fan air, sothat the streams of fan air are turned forwardly more than they would beif the deflector plates were not provided on the outer doors. Thesideplates 60 on the outer doors channel the streams of fan air alongthe doors and therefore reduce the loss of reverse thrust which wouldresult from flow of fan air through the gaps between the edges of theouter doors.

When thrust reversal is no longer required motors 104 are operated torotate the lever arms 74, 76 back to the FIG. 2 position, whichinitially moves the inner doors toward cowling 18 as the outer doors aremoved away from said cowling and then simultaneously retracts both theinner and outer doors after they rotate past the position illustrated inH6. 3. A second limit switch is actuated to stop motors 104 when thedoors reach the retracted position.

The described actuation system is designed so that when the inner doors34 are fully deployed the spacing between the outer doors 36 and cowling18 accommodates the full flow of fan air from passage 28 withoutincreasing the pressure within said passage to a level which mighteffect the speed of rotation of the fan of the jet engine within housing10, and when the outer doors are in the position illustrated in FIG. 3they are actually deployed farther than necessary. Thus when the doorsare deployed the outer doors reach a position which can accommodate theflow of fan air from passage 28, without causing overpressure, beforesaid passage is completely blocked by the inner doors. Also, when thedoors are retracted the inner doors move away from housing 10 andpartially open passage 28 before the outer doors begin to close openings30. Hence the pressure within the portion of passage 28 forward of theinner doors remains substantially the same as the doors are beingdeployed and retracted.

What is claimed as new and useful and desired to be secured by U.S.Letters Patent is:

1. In an aircraft having a turbofan engine, the combination comprising:

a tubular housing fixedly disposed around said engine and extending aftof the fan section thereof, primary exhaust gas of said engine beingdischarged to the atmosphere from the aft end of said housing;

a tubular cowling fixedly disposed in spaced relation around saidhousing and defining therewith a passage through which fan air of saidengine is discharged to the atmosphere, a plurality of openings beingcircumferentially spaced about and extending through the wall of saidcowling aft of the fan section of said engine;

a plurality of inner-thrust-reversing doors circumferentially spacedabout the inner side of said cowling and each pivoted at one edgethereof to said cowling adjacent the aft edge of a respective one ofsaid openings, said inner doors being movable between (1) a retractedposition wherein they extend longitudinally of said cowling andrespectively lie over said openings and (2) a deployed position whereinthey project inwardly from said cowling and their free ends are adjacentsaid housing so that fan air flowing tlirough said passage is therebydeflected through said openings;

plurality of outer-thrust-reversing doors circumferentially spaced aboutthe outer side of said cowling and each pivoted at one edge thereof tosaid cowling adjacent the aft edge of a respective one of said openings,said outer doors being movable between (1) a retracted position whereinthey extend longitudinally of said cowling and respectively lie oversaid openings and (2) a deployed position wherein they project outwardlyfrom said cowling and deflect in a forward direction fan air flowingthrough said openings; and

means operatively associated with said inner and outer doors forsimultaneously moving the same between said retracted and deployedpositions thereof, said means being arranged so that during deploymentsaid inner doors reach said deployed position thereof after said outerdoors are fully deployed and so that during retraction said inner doorsmove away from said deployed position thereof before said outer doorsmove toward said cowling.

2. The combination defined in claim ll wherein said means for movingsaid inner and outer doors between said retracted and deployed positionsthereof comprise:

a drive shaft mounted on said cowling adjacent the forward edge of eachopening therein and rotatable about its own longitudinal axis, said axisbeing substantially parallel with the axis of rotation of the adjacentpair of inner and outer doors;

means for simultaneously rotating said shafts in the same direction at aselected time;

first and second lever arms fixedly connected at one end to each driveshaft and extending laterally therefrom;

first and second links respectively pivoted at one end to the free endsof each associated pair of said first and second lever arms for rotationabout axes substantially parallel with the longitudinal axis of theshaft on which said lever arms are mounted, the other ends of said firstand second links being respectively pivoted to the adjacent pair of saidinner and outer doors, said first and second lever arms being positionedon their drive shafts so that when said doors are deployed said secondlinks are respectively centered relative to said second lever armsbefore said first links are centered relative to said first lever anns.

3. The combination defined in claim ll wherein sidewalls extend alongthe longitudinally extending edges of each of said outer doors, saidsidewalls being mounted on the inner side of said outer doors anddisposed substantially perpendicular to the adjacent portion thereof.

4. The combination defined in claim 1 wherein deflector plates arerespectively fixedly mounted on the inner side of said outer doorsadjacent the free ends thereof, said deflector plates extendingcircumferentially of said outer doors and being disposed substantiallyperpendicular thereto.

5. in an aircraft having a turbofan engine, the combination comprising:

a tubular housing fixedly disposed around said engine and extending aftof the fan section thereof, primary exhaust gas of said engine beingdischarged to the atmosphere from the aft end of said housing;

a tubular cowling fixedly disposed in spaced relation around saidhousing and defining therewith a passage through which fan air of saidengine is discharged to the atmosphere, a plurality of openings beingcircumferentially spaced about and extending through the wall of saidcowling aft of the fan section of said engine;

a plurality of inner thrust reversing doors circumferentially spacedabout the inner side of said cowling and each pivoted at one edgethereof to said cowling adjacent the aft edge of a respective one ofsaid openings, said inner doors being movable between (1) a retractedposition wherein they extend longitudinally of said cowling andrespectively lie over said openings and (2) a deployed position whereinthey project inwardly from said cowling and their free ends are adjacentsaid housing so that fan air flowing through said passage is therebydeflected through said openings; plurality outer thrust reversing doorscircumferentially spaced about the outer side of said cowling and eachpivoted at one edge thereof to said cowling adjacent the aft edge of arespective one and said openings, said outer doors being movable between(1) a retracted position wherein they extend longitudinally of saidcowling and respectively lie over said openings and (2) a deployedposition wherein they project outwardly from said cowling and deflect ina forward direction fan air flowing through said openings;

sidewalls respectively extending along the longitudinal edges of each ofsaid outer doors and proiecting inwardly from the inner side thereof insubstantially perpendicular relation therewith;

said outer doors adjacent the free ends thereof respectively havingdeflector plates fixedly mounted on the inner sides thereof, saiddeflector lates extendin circumferentially of said outer doors and beingdispose substantially perpendicular thereto; and

means operatively associated with said inner and outer doors forsimultaneously moving the same between said retracted and deployedpositions thereof.

1. In an aircraft having a turbofan engine, the combination comprising:a tubular housing fixedly disposed around said engine and extending aftof the fan section thereof, primary exhaust gas of said engine beingdischarged to the atmosphere from the aft end of said housing; a tubularcowling fixedly disposed in spaced relation around said houSing anddefining therewith a passage through which fan air of said engine isdischarged to the atmosphere, a plurality of openings beingcircumferentially spaced about and extending through the wall of saidcowling aft of the fan section of said engine; a plurality ofinner-thrust-reversing doors circumferentially spaced about the innerside of said cowling and each pivoted at one edge thereof to saidcowling adjacent the aft edge of a respective one of said openings, saidinner doors being movable between (1) a retracted position wherein theyextend longitudinally of said cowling and respectively lie over saidopenings and (2) a deployed position wherein they project inwardly fromsaid cowling and their free ends are adjacent said housing so that fanair flowing through said passage is thereby deflected through saidopenings; plurality of outer-thrust-reversing doors circumferentiallyspaced about the outer side of said cowling and each pivoted at one edgethereof to said cowling adjacent the aft edge of a respective one ofsaid openings, said outer doors being movable between (1) a retractedposition wherein they extend longitudinally of said cowling andrespectively lie over said openings and (2) a deployed position whereinthey project outwardly from said cowling and deflect in a forwarddirection fan air flowing through said openings; and means operativelyassociated with said inner and outer doors for simultaneously moving thesame between said retracted and deployed positions thereof, said meansbeing arranged so that during deployment said inner doors reach saiddeployed position thereof after said outer doors are fully deployed andso that during retraction said inner doors move away from said deployedposition thereof before said outer doors move toward said cowling. 2.The combination defined in claim 1 wherein said means for moving saidinner and outer doors between said retracted and deployed positionsthereof comprise: a drive shaft mounted on said cowling adjacent theforward edge of each opening therein and rotatable about its ownlongitudinal axis, said axis being substantially parallel with the axisof rotation of the adjacent pair of inner and outer doors; means forsimultaneously rotating said shafts in the same direction at a selectedtime; first and second lever arms fixedly connected at one end to eachdrive shaft and extending laterally therefrom; first and second linksrespectively pivoted at one end to the free ends of each associated pairof said first and second lever arms for rotation about axessubstantially parallel with the longitudinal axis of the shaft on whichsaid lever arms are mounted, the other ends of said first and secondlinks being respectively pivoted to the adjacent pair of said inner andouter doors, said first and second lever arms being positioned on theirdrive shafts so that when said doors are deployed said second links arerespectively centered relative to said second lever arms before saidfirst links are centered relative to said first lever arms.
 3. Thecombination defined in claim 1 wherein sidewalls extend along thelongitudinally extending edges of each of said outer doors, saidsidewalls being mounted on the inner side of said outer doors anddisposed substantially perpendicular to the adjacent portion thereof. 4.The combination defined in claim 1 wherein deflector plates arerespectively fixedly mounted on the inner side of said outer doorsadjacent the free ends thereof, said deflector plates extendingcircumferentially of said outer doors and being disposed substantiallyperpendicular thereto.
 5. In an aircraft having a turbofan engine, thecombination comprising: a tubular housing fixedly disposed around saidengine and extending aft of the fan section thereof, primary exhaust gasof said engine being discharged to the atmosphere from the aft end ofsaid housing; a tubular cowling fixedly disposed in spaced relationaround said Housing and defining therewith a passage through which fanair of said engine is discharged to the atmosphere, a plurality ofopenings being circumferentially spaced about and extending through thewall of said cowling aft of the fan section of said engine; a pluralityof inner thrust reversing doors circumferentially spaced about the innerside of said cowling and each pivoted at one edge thereof to saidcowling adjacent the aft edge of a respective one of said openings, saidinner doors being movable between (1) a retracted position wherein theyextend longitudinally of said cowling and respectively lie over saidopenings and (2) a deployed position wherein they project inwardly fromsaid cowling and their free ends are adjacent said housing so that fanair flowing through said passage is thereby deflected through saidopenings; a plurality outer thrust reversing doors circumferentiallyspaced about the outer side of said cowling and each pivoted at one edgethereof to said cowling adjacent the aft edge of a respective one andsaid openings, said outer doors being movable between (1) a retractedposition wherein they extend longitudinally of said cowling andrespectively lie over said openings and (2) a deployed position whereinthey project outwardly from said cowling and deflect in a forwarddirection fan air flowing through said openings; sidewalls respectivelyextending along the longitudinal edges of each of said outer doors andprojecting inwardly from the inner side thereof in substantiallyperpendicular relation therewith; said outer doors adjacent the freeends thereof respectively having deflector plates fixedly mounted on theinner sides thereof, said deflector plates extending circumferentiallyof said outer doors and being disposed substantially perpendicularthereto; and means operatively associated with said inner and outerdoors for simultaneously moving the same between said retracted anddeployed positions thereof.